#include <iostream> #include <uuid/uuid.h> #include <ctime> #include <fstream> #include <sstream> #include <chrono> #include <string.h> using namespace std; void retrieveUuid1(char *uuidValue); char *getTimeNow(); void writeFile3(); void readFile4(); int main() { writeFile3(); return 0; } void readFile4() { fstream rFile("log.txt",ios::in); if(!rFile.is_open()) { cout<<"Open log.txt failed!"<<endl; } string line; unsigned num=0; while(getline(rFile,line)) { ++num; if(num%1000000==0) { cout<<"Num is "<<num<<",value is "<<line<<",now is "<<getTimeNow()<<endl; } } rFile.close(); cout<<"Now finished in openLog4() and now is "<<getTimeNow()<<endl; } void writeFile3() { fstream wFile("log.txt",ios::app|ios::out); if(!wFile.is_open()) { cout<<"Create or open log.txt failed!"<<endl; } unsigned num=0; stringstream ss; char *uuidValue=(char*)malloc(40); unsigned int loops=100; unsigned int loopTimes=1000000; string str; chrono::time_point<chrono::system_clock> startTime; chrono::time_point<chrono::system_clock> endTime; for(int i=0;i<loops;i++) { startTime=chrono::system_clock::now(); for(int j=0;j<loopTimes;j++) { ++num; retrieveUuid1(uuidValue); str=to_string(num); str.append(","); str.append(uuidValue); ss<<str<<endl; } wFile<<ss.str()<<endl; ss=stringstream(); endTime=chrono::system_clock::now(); cout<<"Num is "<<num<<",now is "<<getTimeNow()<<endl; cout<<"Time cost " <<chrono::duration_cast<chrono::seconds>(endTime-startTime).count()<<" seconds," <<chrono::duration_cast<chrono::milliseconds>(endTime-startTime).count()<<" milliseconds," <<chrono::duration_cast<chrono::microseconds>(endTime-startTime).count()<<" microseconds," <<chrono::duration_cast<chrono::nanoseconds>(endTime-startTime).count()<<" nanoseconds"<<endl<<endl; } free(uuidValue); wFile.close(); cout<<"Finished in log3() and now is "<<getTimeNow()<<endl; } void retrieveUuid1(char *uuidValue) { uuid_t newUUID; uuid_generate(newUUID); uuid_unparse(newUUID,uuidValue); } char *getTimeNow() { char *dtValue=(char*)malloc(20); time_t rawTime=time(NULL); struct tm tmInfo=*localtime(&rawTime); strftime(dtValue,20,"%Y%m%d%H%M%S",&tmInfo); return dtValue; }
Compile
g++ -g -std=c++2a -I. h1.cpp -o h1 -luuid
Run
原文链接: https://www.cnblogs.com/Fred1987/p/15710211.html
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